1. Field of the Invention
The present invention relates to an electronic device, and more particularly to a hand-writing entry device.
2. Related Background Art
In an electronic device powered by a battery, a power saving approach has been taken by providing a stand-by mode and an operation mode. In one example, in the stand-by mode to wait an input, a clock frequency supplied to a CPU and an operation/control unit is lowered. By this method, an interrupt request time of an interval timer for key scan may be elongated. Thus, in an entry device such as a keyboard in which input information is identified only after several times of scan, even if the key scan interval is long in the stand-by mode, the clock frequency may be returned to the normal one for the operation mode after the key entry has been detected by the first key scan. Accordingly, the device operates effectively.
However, where the entry device is a digitizer, for example, which enters information by hand writing, the precision of position information given by the input directly relates to the precision of character recognition. Accordingly, even if the CPU clock is returned to the normal clock frequency at the first input timing, the position information of the input data cannot be obtained with a sufficient precision and the precision of character recognition is lowered. In order to solve the above problem, it is necessary to always keep the CPU clock at the high frequency of the operation mode. This leads to another problem of increasing a power consumption.